He required of definition that the definiens (the statement of definition) should be synonymous with the definiendum (the expression or concept being defined) but contain no terms in common with it.

The former is defined, by the ancient logic texts I love, as when a definition uses the same terms in the definiens as in the definiendum.

The use of the definiens and of the definiendum, violation of a law of nature, both assume that the operation of a law of nature is logically compatible with the occurrence of an exception to its operation.